New biomechanical footwear relieves knee OA pain

A new biomechanical footwear system was effective in relieving pain and improving physical function among patients with knee osteoarthritis, according to results of a randomized controlled trial presented at the ACR/ARHP 2018 Annual Meeting.

“Biomechanics play an important role in knee OA and several biomechanical treatments for knee OA have emerged,” Stephan Reichenbach PhD, head of research at the Institute of Social and Preventive Medicine, University of Bern, Switzerland, said during a presentation. “The Cochrane Review of 2015 ruled that the evidence of their effectiveness is still inconclusive.”

The experimental biomechanical footwear system (AposTherapy) is a regular shoe with two adjustable convex pods that are screwed into the soles. The pods have different degrees of convexity and diameters that are designed to retrain neuromuscular control, improve functional alignment while walking and unload pressure from the affected areas, thereby reducing pain. Certified physical therapists individually calibrate the footwear system based on patients’ symptoms and observed gait pattern.

Previously, results of a small, non-randomized controlled trial showed that the biomechanical footwear system substantially improved pain among patients with knee OA. To further investigate, Reichenbach and colleagues conducted a randomized controlled trial comparing the efficacy of the footwear system with the sham device, which has flat pods.

The researchers randomly assigned 111 patients with knee OA to use the experimental footwear system and 109 patients to the sham device. At baseline, the average WOMAC pain score was 4.1.

The patients were instructed to use the footwear for 30 minutes per day during week 1, increasing its use by 10 minutes per day each week thereafter, reaching a maximum of 5 hours per day at week 24. Each patient’s footwear was recalibrated after weeks 4, 8, 12 and 16. However, because the sham device does not have adjustable pods, technicians pretended to make adjustments to these shoes.

By week 24, six patients assigned to the experimental footwear system and 13 assigned to the sham device discontinued use.

A 30% reduction in pain was reported by 92% of patients assigned to the experimental footwear system vs. 58% assigned to the sham device (adjusted risk difference of 34%; 95% CI, 23%-45%). Similarly, a 50% reduction was reported by 82% of patients in the experimental footwear group vs. 42% in the sham device group (adjusted risk difference of 41%; 95% CI, 28%-52%).

The safety profiles were similar, with 18 possibly treatment-related adverse events in the biomechanical footwear group and 17 possibly treatment-related adverse events in the sham footwear group. No serious treatment-related adverse events were reported.

“This trial suggests that the new biomechanical footwear system is both efficacious and safe in relieving knee pain and disability with knee OA,” Reichenbach concluded.